J/A+AS/115/75 Optical astrometry of Benchmark radio sources. III (Costa+, 1996)
Optical astrometry of Benchmark radio sources. III. Positions of 35
southern extragalactic radio sources with respect to the International
Reference Stars catalogue.
Costa E., Loyola P.
<Astron. Astrophys. Suppl. Ser. 115, 75 (1996)>
=1996A&AS..115...75C 1996A&AS..115...75C (SIMBAD/NED BibCode)
ADC_Keywords: Radio sources ; QSOs ;
Keywords: astrometry - radio continuum: stars - reference system -
quasar: Q0523-570
Description:
Optical positions, relative to the International Reference Stars
catalogue (IRS), and therefore in the system of the FK5, have been
obtained for the optical counterparts of 35 extragalactic radio
sources south of δ~+3deg.
Many of these sources are being considered as possible
Benchmark objects for the establishment of a quasi-inertial unified
radio/optical reference frame. Precision levels better than 0.2" in
both coordinates were achieved. A comparison with VLBI radio
positions available for these sources is presented. We give evidence
for a possible offset in RA between the radio and optical reference
frames.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1 79 35 Optical positions in the FK5 system of
35 extragalactic radio sources
table2 40 15 Comparison in the FK5 system with the radio
positions of the NRL/USNO Survey
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Byte-by-byte Description of file: table1
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Bytes Format Units Label Explanations
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4- 11 A8 --- IAU IAU designation of the source
17- 18 I2 h RAh Right ascension (J2000)
20- 21 I2 min RAm Right ascension (J2000)
23- 28 F6.3 s RAs Right ascension (J2000)
32- 35 F4.2 arcsec e_RAs ? Error on right ascension:
σ(αcosδ) (1)
40 A1 --- DE- Declination sign
41- 42 I2 deg DEd Declination (J2000)
44- 45 I2 arcmin DEm Declination (J2000)
47- 51 F5.2 arcsec DEs Declination (J2000)
55- 58 F4.2 arcsec e_DEs ? Error on declination:
σ(cosδ)(1)
63- 70 A8 "DD/MM/YY" Date Epoch of observation
75- 78 A4 --- Notes Notes
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Note (1): Determined as described in Costa and Loyola 1992
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Byte-by-byte Description of file: table2
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Bytes Format Units Label Explanations
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1- 8 A8 --- IAU IAU designation of the source
24- 28 F5.2 arcsec DeltaRA Difference with the VLBI radio position
from the NRL/USNO Survey (Fey et al. 1994);
NRL-CL (CL=this paper);
Delta α cos δ
36- 40 F5.2 arcsec DeltaDE Difference with the VLBI radio position
from the NRL/USNO Survey (Fey et al. 1994);
NRL-CL (CL=this paper); Delta δ
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Table 2 (continued):
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Mean residual -0.24 0.04
Sigma 0.27 0.22
Standard error 0.07 0.06
Nx of common objects 15
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References:
Costa E. and Loyola P. 1992, A&AS 96, 183 =1992A+AS...96..183C 1992A+AS...96..183C
Fey A.L., Russell J.L., de Vegt C. et al. 1994, AJ 107, 385
=1994AJ....107..385F 1994AJ....107..385F
(End) Simona Mei [CDS] 06-Sep-1995